1. Field of the Invention
The present invention relates to a pipe connecting apparatus for connecting a first pipe member having an inner peripheral face and an axis with a second pipe member inserted into the first pipe member. More particularly, the invention relates to a pipe connecting apparatus for use in a pipe system of a fluid transport pipe such as a water pipe installed under the ground in order to prevent inadvertent withdrawal of the second pipe member inserted into and connected with the first pipe member by an external tensile force in the axial direction of the pipe which may be applied to the system due to an earthquake, differential settlement or the like.
2. Description of the Related Art
According to a conventional pipe connecting apparatus, as shown in FIGS. 12 and 13, over an insertion pipe portion 51 (an example of the second pipe member) inserted into and connected with a receiver pipe portion 50 (an example of the first pipe member), there are fitted an elastic seal 52 capable of sealing between an inner peripheral face of the receiver pipe portion 50 and an outer peripheral face of the insertion pipe portion 51 and a press ring 53 having a substantially C-shaped configuration as seen in the axial direction X of the pipe, the press ring 53 being capable of compressing the elastic seal 52 from the axial direction X and also of elastically deformable to be reduced in its diameter. A first fastener means 54 is provided for fastening the press ring 53 and the receiver pipe portion 50 together in the pipe axial direction X. In addition, in many cases, between the outer peripheral face of the insertion pipe portion 51 and the inner peripheral face of the press ring 53, there is interposed a retainer ring 55 having a substantially C-shaped configuration as seen from the pipe axial direction and capable of being elastically deformed to be reduced in its diameter until the ring 55 is pressed against the outer peripheral face of the insertion pipe portion 51.
As described above, the press ring 53 is provided as the C-shaped ring having one cutout portion in the periphery thereof which is capable of elastically deformable to be reduced in its diameter. This press ring 53 integrally includes, at opposed free peripheral ends thereof, a pair of connecting pieces 53A opposed to each other in a direction substantially normal to the pipe axial direction X (i.e. along the peripheral direction of the pipe). And, across these connecting pieces 53A, there is provided a second fastener means 56 which is fastened in said normal direction to elastically deform the press ring 53 in the diameter-reducing direction, thus elastically deforming the retainer ring 55 in the diameter-reducing direction.
More particularly, at a plurality of peripheral portions at an end of the outer peripheral face of the receiver pipe portion 50, there are integrally formed first connecting projections 50A. On the other hand, at corresponding plural peripheral portions in the outer peripheral face of the press ring 53, there are integrally formed second connecting projections 53B. And, the first fastener means 54 described above comprises plural sets of T-shaped bolts 54A and nuts 54B fitted across these respective paired connecting projections 50A, 53B of the receiver pipe portion 50 and the press ring 53. The second fastener means 56 comprises a pair of a bolt 56A and a nut 56 which are inserted and fitted across the opposed connecting pieces 53A of the press ring 53 described above.
Further, in many cases, an inner peripheral face 53a of the press ring 53 includes a tapered face adapted for further pressing the retainer ring 55 against the outer peripheral face of the insertion pipe portion 51 in response to a possible mutual withdrawal displacement between the receiver pipe portion 50 and the insertion pipe portion 51.
With the conventional pipe connecting apparatus described above, in connecting the receiver pipe portion 50 and the insertion pipe portion 51, first, the press ring 53 which is still in a diameter-expanded condition and supporting the retainer ring 55 will be fitted over the insertion pipe portion 51 which was inserted in advance into the receiver pipe portion 50. Next, the second connecting projections 53B of the press ring 53 and the first connecting projections 50A of the receiver pipe portion 50 retaining the elastic seal 52 therein will be temporarily connected and loosely fastened together. Thereafter, the insertion pipe portion 51 will be inserted by a predetermined length into the receiver pipe portion 50 through the retainer ring 55 and the elastic seal 52 retained to the inner peripheral face of the press ring 53. Then, the bolts 54 and the nuts 54B of the first fastener means 54 will be fastened so as to fixedly connect the first connecting projections 50A of the receiver pipe portion 50 and the second connecting projections 53B of the press ring 53. At the same time, with the mutually approaching movement between the two pipe portions 50, 51 associated with the above-described fixing and connecting operation thereof, the elastic seal 52 will be compressed in the pipe axial direction X so as to seal between the inner peripheral face of tie receiver pipe portion 50 and the outer peripheral face of the insertion pipe portion 51.
After completion of the compressive sealing operation of the elastic seal 52, the bolt 56A and nut 56B of the second fastener means 56 fitted across the connecting pieces 53A of the press ring 53 will be fastened, so that this ring 53 will be elastically deformed in the diameter-reducing direction. This elastic deformation of the press ring 53 causes elastic diameter-reducing deformation of the retainer ring 55, so that the retainer ring 55 will `bite into` the outer peripheral face of the insertion pipe portion 51.
In summary, the conventional pipe connecting apparatus requires the fastening operation of the first fastener means 54 in the pipe axial direction X for compressing the elastic seal 62 and the further fastening operation of the second fastener means 56 in the pipe radial direction for elastically compressing the retainer ring 65 for the bite-in engagement. In this manner, the assembly operation of the conventional apparatus is troublesome as requiring many steps. Further, the apparatus requires a significant number of components for providing these fastener means; and also, in connection with this requirement, it is also necessary to form a number of connecting projections and bolt-inserting holes in the receiver pipe portion 50 and the press ring 53, respectively. This tends to result in complexity of the entire construction as well as increase in the manufacture cost.
Moreover, if the second fastener means 56, rather than the first fastener means 54, is fastened first by an error, the retainer ring 55 will bite into the outer peripheral face of the insertion pipe portion 51. Then, if the first fastener means 54 is fastened under this condition, the resultant mutual approaching displacement between the press ring 53 and the receiver pipe portion 50 will cause displacement of the insertion pipe portion 51 together with the press ring 53 via the retainer ring 55, so that the pipe portion 51 will be inserted further into the receiver pipe portion 50, thus leading to a change in the insertion length of this insertion pipe portion 51 into the receiver pipe portion 50. Moreover, if the leading end of the insertion pipe portion 51 comes into abutment against a projection 50B on the inner peripheral face of the receiver pipe portion 50, any further fastening operation will be disabled, thus inviting sealing defect due to insufficient compression of the elastic seal 2.
In view of the above-described state of the art, a primary object of the present invention is to provide a pipe connecting apparatus which allows the connection between the first pipe member and the second pipe member inserted therein to be effected reliably and efficiently for providing reliable sealed connection therebetween with maximally maintaining the originally set insertion length of the latter relative to the former and which also allows simple construction and reduction in its manufacture costs through reduction in the number of components needed for constructing the apparatus.